One or more aspects relate, in general, to processing within a computing environment, and in particular, to processing associated with address translation data structures of a virtual environment.
In computing environments that support virtualization technology, dynamic address translation (DAT) may be performed during a memory reference to translate a virtual address into a corresponding real or absolute address. This translation typically includes a walk, referred to as a page or DAT walk, of multiple levels of address translation tables in order to determine the real address. This is time consuming, and thus, to improve performance for future translation requests, the virtual address to real or absolute address mapping is stored in an entry of a structure associated with address translation, such as a translation look-aside buffer (TLB) or other such structure.
The translation look-aside buffer is a cache used by the memory management hardware to improve virtual address translation speed. The next time translation for a virtual address is requested, the TLB is checked. If the translation is in the TLB, there is a TLB hit and the real or absolute address is retrieved from the TLB. Otherwise, the DAT walk is performed once again.
At times, it is necessary to purge some or all of the TLB entries used by a particular processor. When this occurs, it is expensive in terms of performance to perform address translation.